Small sized, light weight, high energy density and repeatedly rechargeable lithium ion secondary cells, electric double layer capacitors, and other electrochemical devices are rapidly growing in demand due to their properties. Lithium ion secondary cells are being utilized in mobile phones, notebook type personal computers, and other fields due to their relatively large energy density, while electric double layer capacitors can be rapidly charged and discharged, so are being utilized as small sized power supplies for memory backup of personal computers etc. Furthermore, electric double layer capacitors are promising in terms of application as large power supplies for electric vehicles. Further, redox capacitors utilizing an oxidation reduction reaction of the surface of metal oxides or a conductive polymer (pseudo electric double layer capacitor capacity) are also gathering attention due to the size of their capacities.
These electrochemical devices are being asked to be improved much more such as being reduced in resistance, increased in capacity, and improved in mechanical properties and productivity along with the expansion and development of their applications. Among these, methods of production of electrochemical device electrodes higher in productivity are also being sought. Various improvements are being made to methods of production enabling high speed formation and electrochemical device electrode materials complying with these methods of production.
Electrochemical device electrodes generally are made of an active material layer comprising activated carbon, lithium metal oxide, graphite, a metal alloy, or other electrode active material and a conductive material bonded by a binder all laminated on a current collector. As the method of forming this active material layer, Japanese Patent Publication (A) No. 2005-78943 (U.S. Patent Publication No. 2005-064096A) describes press forming composite particles comprised of a particulate electrode active material and particulate conductive aid bonded by a binder. Further, WO2005/124801 describes a method of press forming an electrode material comprised of spherical particles including an electrode active material and thermoplastic binder.